Bill and Cathy built a new home in 1985 at a cost of $90,000. They paid 20% of the cost to build the home themselves and financed the rest. They paid off the mortgage in 15 years. They used $35,000 from Bill's inheritance to upgrade the home in 2004. When they sold the home for $335,000 in 2006, what was the value of their equity?
A. $35,000
B. $90,000
C. $210,000
D. $245,000
E. $335,000
F. It depends on the rate of interest on the mortgage they had